An illumination device or the like is developed which excites a fluorescent substance contained in a fluorescent substance layer by excitation light emitted from an excitation light source and generates fluorescence from the fluorescent substance. Such an illumination device is disclosed in PTL 1 to PTL 3.
PTL 1 discloses an illumination device in which spot feature of illumination light emitted from a fluorescent substance layer is improved. In the illumination device, the spot feature of the illumination light is improved by refracting light propagating into the fluorescent substance layer by using a hollow body.
PTLs 2 and 3 disclose an illumination device in which color unevenness of illumination light is reduced. In PTL 2, the illumination device in which a scattering layer that scatters light is disposed on a light emitting surface side of a fluorescent substance layer is proposed. In the illumination device, color unevenness of illumination light is reduced by scattering excitation light and fluorescence contained in irradiation light by using a scattering layer.
In addition, PTL 3 proposes the illumination device including a fluorescent substance layer provided with a plurality of holes penetrated in a thickness direction. In the illumination device, propagation of a part of light is blocked by a hole provided in the fluorescent substance layer, and thereby, a yellow ring may not be generated at an outer peripheral portion of the fluorescent substance layer, and color unevenness of illumination light may be reduced.